1. Field of the Invention
This invention relates to an apparatus for automatically selecting one from color pellets of different colors and automatically supplying the selected color pellet to an injection molding machine.
2. Description of the Related Art
To realize an efficient flexible manufacturing system in obtaining polychromatic molded products by a common injection molding machine, it is currently of urgent necessity for our industry to develop an automatic selecting and supplying apparatus for automatically executing the pellet selecting operation which has conventionally been performed by hand.
One example among the few developed technologies is an automatic color pellet selecting method disclosed in Japanese Patent Publication No. 35372/1987.
According to this prior method, every time change-over of color pellets is made, a cleaning material and a selected color pellet are automatically supplied in order to an inlet of an injection molding machine from a cleaning material hopper and a number of color pellet hoppers. In response to an instruction from a control unit, the individual hoppers are revolved on a common circular track until a desired hopper arrives at the inlet of the injection molding machine. At the start of molding by a new color pellet, a cleaning material is automatically supplied into the injection molding machine from the cleaning material hopper to clean the previous old color pellet in the injection molding machine as the machine is idly operated a predetermined number of times, whereupon the new color pellet is supplied into the injection molding machine for injection molding.
With this method, although it is possible to improve operativity to a considerable extent, compared to the conventional manual operation, it requires a number of hoppers and a dedicated drive as associated parts of the injection molding machine. This restricts the number of hoppers and the size of the individual hopper so that only a limited mass of pellet and a limited number of colors can be used. Consequently, this prior method is not suitable for use in the production of coupling elements of slide fasteners, which consumes a large mass of each color pellet and needs twenty to thirty kinds of color pellets.